Diorganopolysiloxanes containing itaconate functional groups

ABSTRACT

Diorganopolysiloxanes containing itaconate functional groups include at least one recurring structural unit of the formula (1): ##EQU1## in which a is 1 or 2; the symbol Z is one of the radicals --CH 2  CH(COOR&#39;)CH 2  COOR&#39; and --C(CH 3 )(COOR&#39;)CH 2  COOR&#39;; the symbols R, which may be identical or different, are each a C 1  -C 20  alkyl, vinyl, phenyl or 3,3,3-trifluoropropyl radical, and, in the case where a=2, one of the radicals R may be a hydroxyl group; and the symbols R&#39;, which may be identical or different, are each a C 1  -C 12  monovalent hydrocarbon radical or a C 2  -C 12  monovalent alkoxyalkyl radical, and are useful, e.g., as PVC lubricants and hydraulic fluids; they are facilely prepared by hydrolysis/polycondensation or by hydrosilylation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to novel diorganopolysiloxanes comprisingan itaconate functional group and to the use of such noveldiorganopolysiloxanes, particularly as lubricants for PVC (polyvinylchloride) compositions and as hydraulic fluids.

2. Description of the Prior Art

U.S. Pat. Nos. 4,207,246, 4,322,473 and 4,405,469 describepolyorganosiloxanes modified with an organic moiety including asuccinate functional group and their use as a lubricant for textilefibers, for metal surfaces and as hydraulic fluids.

L. Goodman, in J.A.C.S., 79, 3073 (1957), describes the addition oforganohydrochlorosilanes to ethylenically unsaturated organic monomerssuch as vinyl acetate and allyl acetate. The addition products are thenhydrolyzed to give oils or, after heating, solid resins.

The Goodman article does not describe the addition of itaconate to anorganohydrodichlorosilane or to an organohydrochlorosilane; onlyhydrotrichlorosilanes are featured.

Furthermore, the addition reaction of an ethylenically unsaturatedorganic monomer to a hydrosilane or to a hydropolysiloxane is well knownto this art and is described, for example, in U.S. Pat. Nos. 3,317,369,3,258,477 and 4,160,775.

The prior art, however, is conspicuously devoid of any reference to adiorganopolysiloxane polymer containing an itaconate functional groupwhich exhibits such notable properties as a lubricant for PVC and as ahydraulic fluid.

SUMMARY OF THE INVENTION

Accordingly, a major object of the present invention is the provision ofnovel diorganopolysiloxane polymers comprising, per molecule, at leastone recurring structural unit of the formula: ##EQU2## in which a is 1or 2; the symbol Z is one of the radicals -CH₂ CH(COOR')CH₂ COOR' and-C(CH₃)(COOR')CH₂ COOR'; the symbols R, which may be identical ordifferent, are each a C₁ -C₂₀ alkyl, vinyl, phenyl or3,3,3-trifluoropropyl radical, and, in the case where a=2, one of theradicals R may be a hydroxyl group; and the symbols R', which may beidentical or different, are each a C₁ -C₁₂ monovalent hydrocarbonradical or a C₂ -C₁₂ monovalent alkoxyalkyl radical.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

More particularly according to the present invention, the "other" siloxyrecurring units of the subject novel diorganopolysiloxanes preferablyhave the formula: ##EQU3## in which R is defined as above and b is equalto 2 or 3.

The diorganopolysiloxanes according to this invention are preferablylinear or cyclic polymers having the following formulae (2) and (3):##STR1## in which the symbols R and Z are as defined above; the symbolsZ', which may be identical or different, are each a radical R or Z; r isan integer ranging from 0 to 500, inclusive; s is an integer rangingfrom 0 to 50, inclusive, and, if s is 0, at least one of the symbols Z'is Z; and ##STR2## in which R and Z are as defined above; u is aninteger ranging from 1 to 20, inclusive; t is an integer ranging from 0to 20, inclusive; and t+u is greater than or equal to 3.

The preferred alkyl radicals R are methyl, ethyl, propyl, n-butyl,n-octyl and 2-ethylhexyl radicals. Preferably, at least 80% of thenumber of the radicals R are methyl radicals.

The radicals R' are advantageously selected from among:

(i) C₁ -C₁₂ alkyl radicals, such as methyl, ethyl, n-propyl, isopropyl,n-butyl, 2-ethylhexyl, heptyl and dodecyl radicals;

(ii) C₆ -C₁₂ aryl, alkylaryl and arylalkyl radicals, such as phenyl,benzyl and tolyl radicals; and

(iii) C₂ -C₁₂ alkoxyalkyl radicals, such as methoxymethyl, ethoxymethyland 2-methoxyethyl radicals.

The more particularly preferred diorganopolysiloxanes of this inventionare random or block polymers of formulae (1), (2) and (3) exhibiting atleast one of the following characteristics:

R and R' are methyl;

r ranges from 5 to 50, inclusive;

s ranges from 2 to 20, inclusive; and

t+u ranges from 3 to 10, inclusive.

The preferred polymers according to the invention are generally in theform of more or less viscous oils having a viscosity ranging from 2 to500,000 mPa.s, preferably ranging from 5 to 5,000, at 25° C.

The polymers according to the invention may advantageously be preparedby a first process (A), as follows:

In a first step (A₁), an itaconate of the formula:

    CH.sub.2 =C(COOR')CH.sub.2 COOR'                           (4)

in which R' is defined as in formula (1) is added onto ahydroorganochlorosilane of the formula:

    HSiR.sub.a Cl.sub.3-a                                      ( 5)

in which R and a are defined as in formula (1).

An addition product of the formula:

    ZSiR.sub.a Cl.sub.3-a                                      ( 6)

in which R, a and Z are defined as in formula (1) is thus obtained. Zdenotes the two isomeric forms produced depending on whether the siliconatom is bonded to one or the other of the two unsaturated carbon atoms.

Step (A₁) can be carried out in bulk, or in solution in an organicsolvent. The reaction is exothermic. The operation is generally carriedout under reflux of the reaction mixture at a temperature ranging from60° to 140° C. for a period of time which generally ranges from 10minutes to 3 hours.

The silane of formula (5) may be introduced into the itaconate offormula (4), or vice versa, or they may be introduced at the same time.

It is preferred to employ a molar excess (from 10% to 50%) of the silaneof formula (5).

It is also preferred to conduct the reaction in the presence of acatalyst, in order to increase the reaction kinetics. The catalystswhich may be used are those typically employed for carrying out ahydrosilylation reaction. Consequently, those which may be employed, inparticular, are organic peroxides, UV radiations and catalysts based ona metal from the platinum group of the Periodic Table, in particularplatinum, ruthenium and rhodium, in an amount of 20 to 500 ppm(calculated as the weight of metal) relative to the weight of the silaneof formula (5).

Exemplary of such catalysts are platinum metal on carbon black, theplatinum/olefin complexes described in U.S. Pat. Nos. 3,159,601 and3,159,662, chloroplatinic acid, chloroplatinous acid, the complexes ofplatinum and a vinylpolysiloxane which are described in U.S. Pat. No.3,419,593, the platinum complexes having an oxidation state close tozero which are described in U.S. Pat. Nos. 3,715,334, 3,775,452 and3,814,730, and the complexes of platinum with an ethylenicallyunsaturated organic compound which are described in European PatentsNos. EP-A-No. 188,978 and EP-A-No. 190,530.

Upon completion of the reaction, the volatile materials are removed byvacuum distillation. A water vacuum pump generating 0.1 to 3 kPa isgenerally sufficient.

During a second step (A₂), the hydrolysis or cohydrolysis and thepolycondensation of a silane of formula (6) are carried out.

This hydrolysis or cohydrolysis and polycondensation are preferablycarried out in a liquid aqueous phase in an acidic medium (preferablyHCl), or in a basic medium (preferably NH₄ OH), under conditions similarto those employed for the hydrolysis of chlorosilanes, such as describedon pages 193 to 200 of the text by Noll, Chemistry and Technology ofSilicones, Academic Press (1968).

The concentration of acid or of base in water generally ranges from 10%to 30% by weight. The hydrolysis medium always includes at least 2 molesof water per mole of silane, typically from 10 to 100 moles of water.The hydrolysis may be carried out continuously or discontinuously atambient temperature (20° C.), or at a temperature ranging from 5° to 90°C. The hydrolysis may be carried out at a pressure equal to or aboveatmospheric pressure, continuously or discontinuously, with, at least inthe case of the continuous process, reinjection of water in order tomaintain a constant aqueous phase.

In order to prepare polymers of formulae (2) and (3) or mixturesthereof, the silanes of formula (6) are hydrolyzed and polycondensed,optionally in the presence of a dichlorodiorganosilane of the formula:

    R.sub.2 SiCl.sub.2                                         ( 7)

in which R is as defined in formula (1) above.

The polycondensation may be terminated simply by neutralizing thereaction mixture. In this case, the polymers of formula (2) which areobtained are blocked at each of their polymer ends by a hydroxyl groupor by the unit R₂ ZSiO₀.5 if the silane R₂ ZSiCl is employed.

The polycondensation can also be terminated by adding an organosiliconcompound capable of reacting with the terminal hydroxyl groups, such asthe compounds of the formulae:

    R.sub.3 SiCl; R.sub.3 SiNHSiR.sub.3 and R.sub.3 SiOSiR.sub.3

in which the radicals R are as defined in formula (1) above.

The period of hydrolysis may range from a few seconds to several hours.

After hydrolysis, the aqueous phase is separated from the siloxane phaseby any suitable physical means, generally by phase separation andextraction with an organic solvent such as isopropyl ether.

The siloxane phase may be subsequently washed with water and thendistilled, if desired, to separate the linear polymers of formula (2)from the cyclic polymers of formula (3).

To prepare the polymers of formulae (1), (2) and (3) according to asecond process (B) of the invention, it is also possible to use thecorresponding polymer as a starting material in which all of theradicals Z are hydrogen atoms, and to then add an itaconate of formula(4) above by means of a hydrosilylation reaction.

This polymer is referred to in the description that follows as the"polymer containing SiH"; the SiH groups may be present within thepolymer chain and/or at the ends of a polymer chain. These polymerscontaining SiH are well known to the silicone industry and are generallycommercially available.

They are described, for example, in U.S. Pat. Nos. 3,220,972, 3,436,366,3,697,473 and 4,340,709.

This polymer containing SiH can therefore be represented by the formula:##STR3## in which R, r and s are as defined above in the case of formula(2) and the radicals Y, which may be identical or different, are each aradical R or a hydrogen atom; and by the formula: ##STR4## in which R, tand u are as defined above in the case of formula (3).

As in step (A₁) of the process (A), the process (B) therefore employs asimilar hydrosilylation reaction, and it is desirable to carry out thisreaction using the same catalysts as those outlined in step (A.sub.).

This reaction may be carried out in bulk or in an organic solvent at atemperature ranging from normal temperature (25° C.) to 170° C.

The volatile materials are removed upon completion of the reaction byvacuum distillation and/or by extraction.

Process (A) makes it possible to prepare polymers of formula (2)containing hydroxyl endgroups and polymers of formulae (2) and (3)containing radicals R, some of which may be vinyl radicals.

Process (B) makes it possible to prepare polymers of well-definedstructure by judicious selection of the starting polymers containingSiH.

The polymers of formula (1), (2) and (3) have many industrialapplications. They can be used, in particular, as a lubricant for rigidor plasticized PVC (polyvinyl chloride) in a proportion of 0.01 to 2parts by weight, preferably from 0.05 to 1 part by weight, of polymerper 100 parts by weight of PVC resin.

Indeed, the polymers of formulae (1), (2) and (3), while technicallyincompatible, exhibit sufficient compatibility with PVC as not to"bloom" and thus provide a sufficient lubricating action.

The polymers of formulae (1), (2) and (3) can also be used as hydraulicfluids.

In order to further illustrate the present invention and the advantagesthereof, the following specific examples are given, it being understoodthat same are intended only as illustrative and in nowise limitative.

EXAMPLE 1

907 g, i.e., 5.74 moles of methyl itaconate and 129 mg of chloroplatinicacid (H₂ PtCl₆) were charged into a 2-liter three-necked reactorequipped with a condenser, a stirrer and a dropping funnel.

The temperature was increased to 116° C. and 792.5 g (6.89 moles) of CH₃HSiCl₂, i.e., a 20% molar excess relative to the itaconate, were thenintroduced over 65 minutes.

Since the reaction was exothermic, the temperature remained in theregion of 120° C. without any additional heat input. At the end ofaddition, the temperature Was 112° C. The reaction mixture wasmaintained under reflux for 1 hour, 50 minutes, the excess CH₃ HSiCl₂was then distilled off and 1,274 g of a liquid adduct whose boilingpoint was 80° C. at 0.13 kPa were obtained. The weight yield of adductwas 71%.

NMR analysis of the addition product evidenced that it containedapproximately 60 mol % of -CH₂ CH(COOCH₃)CH₂ -COOCH₃ radicals and 40 mol% of -C(CH₃)(COOCH₃)CH₂ COOCH₃ units.

EXAMPLE 2

340 g of an aqueous solution of ammonia NH₄ OH at 20% by weight and 370ml of water were charged into the same three-necked reactor as thatemployed in Example 1. 500 g (1.83 mole) of the adduct obtained inExample 1, dissolved in 500 ml of isopropyl ether, were then introducedover 50 minutes, the temperature being maintained at 25° C.

When the hydrolysis was complete, the mother liquors were separated offand 500 ml of isopropyl ether were added again to promote the phaseseparation. The separated organic solution was washed with water again,was dried and was stripped up to a temperature of 100° C. under a vacuumof 2 kPa.

323 g of a clear oil were then obtained, having a hydroxyl group contentof 1.8% by weight, a viscosity of 35 mPa.s at 25° C. and a weightpercentage of ester functional groups of 54.2%.

EXAMPLE 3

2,800 g of water were charged into a 10-liter three-necked reactor, and903 g (7 moles) of (CH₃)₂ SiCl₂ and 98 g (0.35 mole) of the adductproduced in Example 1 were then introduced over one hour. During theaddition, the temperature increased gradually from 15° to 65° C. Afterthe addition, the reaction mixture was maintained stirred for 30 minutesand the acidic water was separated off. 350 ml of isopropyl ether wereadded, three washings were carried out and the ethereal solution wasconcentrated in a first stage up to 100° C. at atmospheric pressure andthen up to 80° C. under a vacuum of 2.5 kPa.

456 g of a clear and colorless oil which had the followingcharacteristics were then obtained:

    ______________________________________                                        (i)     Viscosity at 25° C.                                                                          20 mPa.s;                                       (ii)    % (by weight) of hydroxyl groups                                                                    1%;                                             (iii)   Weight percentage of ester                                                                          4.8%;                                                   functional group                                                      (iv)    Weight yield of oil   77%.                                            ______________________________________                                    

EXAMPLE 4

Into a 5-liter three-necked reactor were charged 816 g of an oil of theformula: ##STR5## and 948 g of methyl itaconate, all in 1,540 g ofxylene, together with chloroplatinic acid in such amount that there wereapproximately 150 ppm of platinum metal relative to the weight ofsiloxane polymer. The temperature was increased to 145° C. and themedium was maintained at this temperature for 24 hours. The xylene andthe excess methyl itaconate were then distilled off by heating to 140.Cunder a vacuum of 2.5 kPa.

1,370 g of a clear and colorless oil were then obtained, having aviscosity of 950 mPa.s at 25° C. and a weight percentage of esterfunctional groups of 28.2%.

EXAMPLE 5

The following materials were charged at the same time into a one-literreactor fitted with a condenser and a stirrer:

(i) 174 g, i.e., 1.1 mole of methyl itaconate;

(ii) 46 g of a cyclic hydromethylsiloxane of 92% purity, of the formula:##STR6##

(iii) 25 mg of H₂ PtCl₆ (6H₂ O).

The reaction mixture was heated to 135° C. and the temperature wasmaintained at a temperature of from 135° to 160° C. for 1 hour, 30minutes.

The excess methyl itaconate was distilled off by heating the reactionmixture to 160° C. at 0.133 kPa. 146 g of devolatilized oil,orange-yellow in color, were obtained, having a viscosity of 2,240 mPa.sat 25° C., in which the weight percentage of ester was 50%.

The mass spectrum and the UV spectrum (CHCl₃) confirmed that the oilproduced was indeed the compound of the formula: ##STR7## with Z beingan itaconyl radical.

While the invention has been described in terms of various preferredembodiments, the skilled artisan will appreciate that variousmodifications, substitutions, omissions, and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims, including equivalents thereof.

What is claimed is:
 1. A diorganopolysiloxane comprising at least onerecurring structural unit of the formula (1): ##EQU4## in which a is 1or 2; the symbol Z is one of the radicals --CH₂ CH(COOR')CH₂ COOR' or--C(CH₃)(COOR')CH₂ COOR'; the symbols R, which may be identical ordifferent, are each a C₁ -C₂₀ alkyl, vinyl, phenyl or3,3,3-trifluoropropyl radical, and, where a=2, one of the radicals R maybe a hydroxyl group; and the symbols R', which may be identical ordifferent, are each a C₁ -C₁₂ monovalent hydrocarbon radical or a C₂-C₁₂ monovalent alkoxyalkyl radical.
 2. The diorganopolysiloxane asdefined by claim 1, further comprising a siloxy recurring structuralunit of the formula (1'): ##EQU5## in which R is as defined in formula(1) and b is 2 or
 3. 3. The diorganopolysiloxane as defined by claim 1,having the formula (2): ##STR8## in which the symbols R and Z are asdefined in formula (1); the symbols Z', which may be identical ordifferent, are each a radical R or Z; r is an integer ranging from 0 to500; s is an integer ranging from 0 to 50, and, if s is 0, at least oneof the symbols Z' is Z.
 4. The diorganopolysiloxane as defined by claim1, having the formula (3): ##STR9## in which R and Z are as defined informula (1); u is an integer ranging from 1 to 20; t is an integerranging from 0 to 20; and t+u is greater than or equal to
 3. 5. Thediorganopolysiloxane as defined by claim 1, wherein the radicals R aremethyl, ethyl, propyl, n-butyl, n-octyl or 2-ethylhexyl radicals.
 6. Thediorganopolysiloxane as defined by claim 1, wherein the radicals R' areC₁ -C₁₂ alkyl radicals; C₆ -C₁₂ aryl, alkylaryl or arylalkyl radicals;or C₂ -C₁₂ alkoxyalkyl radicals.
 7. The diorganopolysiloxane as definedby claim 3, wherein R and R' are methyl radicals; r ranges from 5 to 50;and s ranges from 2 to
 20. 8. The diorganopolysiloxane as defined byclaim 4, wherein R and R' are methyl radicals; and t+u ranges from 3 to10.
 9. The diorganopolysiloxane as defined by claim 1, having aviscosity ranging from 2 to 500,000 mPa.s at 25° C.
 10. Thediorganopolysiloxane as defined by claim 9, having a viscosity rangingfrom 5 to 5,000 mPa.s at 25° C.
 11. A composition of matter comprisingpolyvinyl chloride and a lubricating amount of the diorganopolysiloxaneas defined by claim
 1. 12. A hydraulic fluid comprising thediorganopolysiloxane as defined by claim 1.